Glock optic issues - need help

[moonshot]

I have a G26.3 for training. I have not kept track of all my rounds, but I am pushing 20,000 rounds through it. I have replaced the slide lock spring and slide lock (due to breakage and loss, respectively) as well as a new RSA (at about 15000 rounds). All internal parts are OEM.

This G26 with both stock G26 and stock G19 mags has been 100% reliable for as long as I have shot it, using WWB 115gr FMJ, 124gr S&B FMJ, 124gr MagTec FMJ, 124gr Fed AE FMJ and for the last several years - 147gr Fed AE FMJFP. I have probably shot at least 5000 rounds of the Fed 147gr FMJFP through it.

This doesn’t include testing 124gr and 147gr HST through it, all without issue.

I now wear glasses and I wanted to try my hand with a red dot. While I detest the idea of aftermarket internal parts on my Glock, I didn’t want to have my OEM slide milled in case I didn’t like using an RDS and wanted to go back to irons.

When I decided to try out an RDS, I selected the Holosun 507C X2. I tried to buy an OEM slide from Glock to have milled, but they would not sell one. OEM slides on-line were few and too expensive - often costing more than a complete firearm.

I started researching after market slides and ended up going with Brownells. They came already milled for an RMR (and the Holosun has the same footprint), so I went with this. Brownells slides got good reviews, my investment was minimal and I still had my OEM slide unaltered.

I mounted my 507C on the Brownells slide, transferred all the original OEM parts from my OEM slide into the Brownells slide, sighted it in at 25 yards and I have since used it in several classes, running perhaps 800 to 1000 rounds of the Fed 147gr AE through it, using multiple G26 and G19 mags.

Since running the Brownells slide with Holosun optic, I have experienced multiple failures. Primarily failures to feed but there may be other failure modes I have not identified. As these are tactical classes, when I have a failure of some kind I perform an immediate action to clear it and continue with that specific string of fire, so I have not carefully identified each specific failure.

These failures are happening with multiple magazines. Feed lips, followers and springs seem fine. The failures only happen after having already shot anywhere from 100 to 175 rounds without issue. The gun is cleaned and properly lubed prior to each class.

I have not been able to narrow the failures down to a specific magazine, although the magazines are well used. They are numbered but I haven’t been able to identify if one is the culprit and I have a hard time picturing all of them going bad at the same time.

The only other things I can think of are the obvious choices - the aftermarket slide, the weight of the optic causing issues or the ammo. These 147gr AE rounds are all relatively new - the ammo involved is from one of two cases I purchased since the last shortage and production ramp up, so QC may have suffered.

All I know is there is something going on that I have not identified. Again, all the parts except the slide itself are OEM. The only aftermarket parts are the slide and the optic. The slide does have a cutout on top in front of the ejection port (similar to a G34). I don’t like it but it’s all Brownells has on their pre-milled G26.3 slides.

I used the optic screws that came with the Brownells slide (as was recommended to me). The longer screw is in the left optic mounting hole and the shorter screw is in the right (over the extractor channel). Hand cycling feels like the Brownells slide may be a little rough compared to my OEM slide, but that is very subjective and may be due to my different grasp due to the optic being in the way.

I don’t know what is going on, but these failures are not acceptable. If I can’t solve the problem, I’m going back to irons, but I like the speed and accuracy my optic provides, especially without my glasses on, so I would like to keep it and run an identical setup on my carry gun (also a G26.3).

Next test will be all new magazines. If that doesn’t solve it, I’m thinking another Brownells slide and another 507C with the same internals mounted on the same frame may be my next test. If that doesn’t work, I’m out of ideas.

Anu suggestions?

[C-grunt]

I have a friend who has had issues with reliability when putting aftermarket slides on previously 100 percent reliable Glocks. One required a different weight spring and had run great ever since. They other had gone through multiple different parts to try and get running and just never got to stock reliability levels.

Id do some research on the Brownells slide and see if it requires/recommends a different weight spring.

[Sam]

With the Holosun mounted on your Brownells slide, use your finger to manually push the safety plunger in the slide, see if it moves freely. Maybe somehow the screw is impeding the full functioning of the plunger, thus affecting the slide's movement.

[Inkslinger]

You seem to be liking the optic. Do you feel that your experience is justification to have your original slide milled? As far as what’s causing the problem, it may be a lot off guessing on everyone’s part. Maybe the lighter slide isn’t liking well worn springs? It could be a rabbit hole. If you can’t find the bottom without driving yourself nuts, mill your oem, sell the Brownells or use it for a training slide to practice malfunctions.

[Ron3]

By 20k rounds you should have replaced every spring in the gun and the striker assembly. And magazine springs.

RSA's every 5k.

I suppose there is a reason you didn't just buy another G26 and have it milled or buy an MOS Glock.

As for where you are now, I'd go ahead and replace any springs you haven't yet, sell the slide for cheap, and work on getting another G26 to put an RDS on.

[L-2]

Thanks for the OP and thread. I considered getting one of those Brownell's G26 slides, but now extra-glad I didn't:
https://www.brownells.com/handgun-pa...rod123831.aspx

I keep hoping Glock will sell its MOS-cut G26gen5 in the U.S., even though I was previously told twice by Glock in 2022, there were no plans to sell it here. But Glock is pretty good at not releasing all its secret marketing insider info. After-all, we've now recently heard Glock intends to sell its G47 to the general public and not only to the "CBP/DHS" customers.
https://eu.glock.com/en/products/pistols/g26-gen5-mos
Yet, I still hope. Also, hopefully, Glock isn't releasing it to the U.S.A. due to it being unreliable.

I can say my G19Gen5MOS with Holosun SCS is reliable with, so far, ~4,000 rounds through it.
I've thought of the G43XMOS instead, but I'd really rather go with a factory Glock 26 (any gen) MOS or just stay with the G19gen5MOS. Glock can keep its G26gen5MOS in Europe and I'll just keep my money here in the USA. I suppose the innocent loser is Holosun as that's likely the company I'd go with again.

It's 12/19/22 and I could change my mind about things at a moment's notice.

I have heard/read mixed experiences of folks trying an aftermarket slide with mixed results, or spending money getting their existing Glock slides modified, again, with mixed results, compromises, or satisfaction.

[moonshot]

I have a friend who has had issues with reliability when putting aftermarket slides on previously 100 percent reliable Glocks. One required a different weight spring and had run great ever since. They other had gone through multiple different parts to try and get running and just never got to stock reliability levels.

Id do some research on the Brownells slide and see if it requires/recommends a different weight spring.

I'll take you advise and check with Brownells, but I suspect their answer will be no change in spring weight. I may try my old RSA, removed after around 15000 rounds. Maybe this will help, but I worry that a lighter weight / weaker spring may end up causing damage to the locking block or locking block pin (which I can replace) or the frame itself. I don't want to solve one problem by creating another.

With the Holosun mounted on your Brownells slide, use your finger to manually push the safety plunger in the slide, see if it moves freely. Maybe somehow the screw is impeding the full functioning of the plunger, thus affecting the slide's movement.

Checked as instructed. Everything worked properly.

You seem to be liking the optic. Do you feel that your experience is justification to have your original slide milled? As far as what’s causing the problem, it may be a lot off guessing on everyone’s part. Maybe the lighter slide isn’t liking well worn springs? It could be a rabbit hole. If you can’t find the bottom without driving yourself nuts, mill your oem, sell the Brownells or use it for a training slide to practice malfunctions.

If I knew the problem was my slide, and only my slide, I might agree to send my OEM slide off to get milled, but I am not yet convinced that the Brownells slide by itself if the cause of my malfunction. I suspect it, but I don't know with certainty.

By 20k rounds you should have replaced every spring in the gun and the striker assembly. And magazine springs.

RSA's every 5k.

I suppose there is a reason you didn't just buy another G26 and have it milled or buy an MOS Glock.

As for where you are now, I'd go ahead and replace any springs you haven't yet, sell the slide for cheap, and work on getting another G26 to put an RDS on.

You might be right. There was a test that was recommended to me by an armoror that indicated my RSA was (and still is) good to go, however I have since learned that they should be replaced sooner - around every 5000 rounds. Other than the slide lock spring, which as a leaf spring is more fragile and something I try and replace every year, I don't think the other springs need replacing until they cause an issue. Again, this is a training gun. I don't mind having an issue as long as it's fixable. My carry gun gets more care, but also gets far fewer rounds thru it.

As for an MOS, they don't yet have a G26 MOS available here in the US, and I would prefer direct milling over any plate mounting.

Thanks for the OP and thread. I considered getting one of those Brownell's G26 slides, but now extra-glad I didn't:
https://www.brownells.com/handgun-pa...rod123831.aspx

I don't yet blame Brownells. They are a good company and I have had excellent service with them. There may be an issue with this particular slide, but Brownells slides for Glocks do get good reviews. Usually, when I see Glocks choke on the range, it's because someone tried to make them "better" with aftermarket parts. This is why I really didn't want to use any slide other than Glock. I am still looking for a reasonably priced Glock OEM slide to have milled so I can keep my original slide unmodified. If nothing else works and I decide I don't want to give up my Holosun, I suppose I'll have to cannibalize a G26, mill its slide and keep the rest as spare parts.

That's actually not a terrible option. I would really like to figure out what is causing the issue and find a solution other than giving up, but at some point the time, effort, frustration and cost of ammo will reach a point where it's not worth the effort. Chalk it up to what a good friend / cop / Glock armorer told me - "It's a Glock. Don't **** with it".

[Ron3]

I didn't know Glock doesn't sell a G26-5 mos in the US yet.

[ssc]

Just some thoughts. I have run glocks hard since the early 90’s. My training/competition gun has around 300,000 round through it. It has been years since I did the armorers class. Glocks are timing machines. So, if something goes out of timing or the balance changes, malfunctions can occur. Some may remember the Glock 22 issues with WML. They changed the flex dynamics of the frame causing malfunctioning. It was a PD in the NW if I remember that had the issue. I recall Glock delivering model 21’s to SBSD and they were malfunctioning. I had friends involved in the fiasco. They finally figured out that the slide was too heavy or light. Can’t remember if it was outrunning the mag springs or what, but they made a few mods to the barrel and slide and all was well. Glock was involved also and were great.

With the above observations, perhaps (just thinking out loud) the weight of the new slide and dot is causing it to run the slide too fast? If so, and your mag springs are near used up, maybe the bullet is not pushed up into the correct position to feed? Not sure of your exact malfunctions. I think trying new mags is a good step. Maybe try weighing the new slide vs a standard slide? Maybe new mag springs? Maybe I missed it, but what malfunctions are you experiencing? Have you measured the new slide to be sure it is in spec?

Just to show how weird things can get, my training gun started to get light primer strikes. After inspecting the gun and ammo it appeared that the depth of the primers was a bit erratic. Sure enough a part in the reloader had worn out. Once that was replaced I had fewer issues but had some. I replaced the striker spring which reduced the issue but still had an occasional issue. I noticed the cups had so much brass shavings embedded in them, that I wondered if it was causing friction with the liner. I replaced the cups and have not had any issues since. Not 100% sure that was the issue but the results are a clue.

Just some random thoughts. If you describe your malfunctions, perhaps we can help more.

Cheers, Steve

[Bruce in WV]

Another thought:if have an optic cut done to your OEM slide, consider switching to the "K" family of Holosuns to take advantage of the rear sight integrated into the body of the dot. Use a "race cut" and avoid the problem of where to put the rear sight.

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